Vehicle mounted DSRC apparatus

Abstract

A vehicle mounted DSRC apparatus is capable of achieving reduction in the size and cost thereof. The vehicle mounted DSRC apparatus includes an ASK data generation part 11 , an I data generation part 21 , a Q data generation part 22 , a first band limiting filter 23 A for band limiting I data and ASK data, a second band limiting filter 24 for band limiting Q data, an ASK low pass filter 12 A for removing harmonic components from the ASK data, first and second low pass filters 25, 26 for removing harmonic components from QPSK data, an ASK modulator 13 for ASK modulating the ASK data, a QPSK modulator 27 for QPSK modulating the QPSK data, and a power amplifier 30 for amplifying output data of the ASK modulator 13 or the QPSK modulator 27 to a desired level thereby to output it to an antenna as an ASK modulated signal and a QPSK modulated signal.

1. A vehicle mounted DSRC apparatus which uses a dedicated short range communications system of an intelligent transport system including ground devices, and which outputs an ASK modulated signal or a QPSK modulated signal in response to transmission data from one of said ground devices,
 said vehicle mounted DSRC apparatus comprising: 
 an antenna for receiving transmission data from said ground devices, and for transmitting said ASK modulated signal and said QPSK modulated signal to said ground devices; 
 an ASK data generation part in an ASK modulation part for generating ASK data in response to said transmission data; 
 a QPSK data generation part in a QPSK modulation part for generating QPSK data containing I data and Q data in response to said transmission data; 
 a first band limiting filter in said QPSK modulation part for band limiting one of said I data and said Q data in said QPSK data and said ASK data; 
 a second band limiting filter for band limiting the other of said I data and said Q data in said QPSK data; 
 an ASK low pass filter for removing harmonic components from said ASK data which has passed through said first band limiting filter; 
 a first low pass filter in said QPSK modulation part for removing harmonic components from said QPSK data which has passed through said first band limiting filter; 
 a second low pass filter for removing harmonic components from said QPSK data which has passed through said second band limiting filter; 
 an ASK modulator for ASK modulating said ASK data from said ASK low pass filter; 
 a QPSK modulator for QPSK modulating said QPSK data from said first and second low pass filters; 
 a power supply for supplying electric power to said ASK modulator and said QPSK modulator; and 
 a power amplifier for amplifying output data from said ASK modulator or said QPSK modulator to a desired level thereby to output it to said antenna as said ASK modulated signal and said QPSK modulated signal. 
 
     
     
       2. A vehicle mounted DSRC apparatus which uses a dedicated short range communications system of an intelligent transport system including ground devices, and which outputs an ASK modulated signal or a QPSK modulated signal in response to transmission data from one of said ground devices,
 said vehicle mounted DSRC apparatus comprising: 
 an antenna for receiving transmission data from said ground devices, and for transmitting said ASK modulated signal and said QPSK modulated signal to said ground devices; 
 an ASK data generation part for generating ASK data in response to said transmission data; 
 a QPSK data generation part for generating QPSK data containing I data and Q data in response to said transmission data; 
 a first band limiting filter in said QPSK modulation part for band limiting one of said I data and said Q data in said QPSK data and said ASK data; 
 a second band limiting filter for band limiting the other of said I data and said Q data in said QPSK data; 
 an ASK low pass filter for removing harmonic components from said ASK data which has passed through said first band limiting filter; 
 a first low pass filter for removing harmonic components from said QPSK data which has passed through said first band limiting filter; 
 a second low pass filter for removing harmonic components from said QPSK data which has passed through said second band limiting filter; 
 an ASK modulator for ASK modulating said ASK data from said ASK low pass filter; 
 a QPSK modulator for QPSK modulating said QPSK data from said first and second low pass filters; 
 a power supply for supplying electric power to said ASK modulator and said QPSK modulator; 
 a power amplifier for amplifying output data from said ASK modulator or said QPSK modulator to a desired level thereby to output it to said antenna as said ASK modulated signal and said QPSK modulated signal; and 
 a filter property switching part for switching the filter property of said first band limiting filter in response to transmission data from one of said ground devices. 
 
     
     
       3. A vehicle mounted DSRC apparatus which uses a dedicated short range communications system of an intelligent transport system including ground devices, and which outputs an ASK modulated signal or a QPSK modulated signal in response to transmission data from one of said ground devices,
 said vehicle mounted DSRC apparatus comprising: 
 an antenna for receiving transmission data from said ground devices, and for transmitting said ASK modulated signal and said QPSK modulated signal to said ground devices; 
 an ASK data generation part for generating ASK data in response to said transmission data; 
 a QPSK data generation part for generating QPSK data containing I data and Q data in response to said transmission data; 
 a first band limiting filter in said QPSK modulation part for band limiting one of said I data and said Q data in said QPSK data and said ASK data; 
 a second band limiting filter for band limiting the other of said I data and said Q data in said QPSK data; 
 an ASK low pass filter for removing harmonic components from said ASK data which has passed through said first band limiting filter; 
 a first low pass filter for removing harmonic components from said QPSK data which has passed through said first band limiting filter; 
 a second low pass filter for removing harmonic components from said QPSK data which has passed through said second band limiting filter; 
 an ASK modulator for ASK modulating said ASK data from said ASK low pass filter; 
 a QPSK modulator for QPSK modulating said QPSK data from said first and second low pass filters; 
 a power supply for supplying electric power to said ASK modulator and said QPSK modulator; and 
 a power amplifier for amplifying output data from said ASK modulator or said QPSK modulator to a desired level thereby to output it to said antenna as said ASK modulated signal and said QPSK modulated signal, wherein said ASK low pass filter comprises said first low pass filter. 
 
     
     
       4. The vehicle mounted DSRC apparatus according to  claim 3 , further comprising:
 an ASK switch inserted between said power supply and said ASK modulator for turning on and off the supply of electric power to said ASK modulator; 
 a QPSK switch inserted between said power supply and said QPSK modulator for turning on and off the supply of electric power to said QPSK modulator; and 
 a modulation system selection part for turning on only one of said ASK switch and said QPSK switch. 
 
     
     
       5. The vehicle mounted DSRC apparatus according to  claim 4 , wherein said modulation system selection part outputs a modulation system instruction signal in response to transmission data from one of said ground devices, determines based on said modulation system instruction signal whether said ASK switch and said QPSK switch are to be turned on or off, and switches the filter property of said first band limiting filter through said filter property switching part. 
     
     
       6. The vehicle mounted DSRC apparatus according to  claim 3 ,
 wherein said ASK modulator comprises said QPSK modulator, and 
 wherein said QPSK modulator includes an input fixing part for fixing the QPSK data input value from said second low pass filter to a prescribed value, said input fixing part being operable to fix the QPSK data input value from said second low pass filter to said prescribed value when said QPSK modulator functions as an ASK modulator in response to transmission data from one of said ground devices. 
 
     
     
       7. The vehicle mounted DSRC apparatus according to  claim 3 ,
 wherein said ASK modulator comprises said QPSK modulator, and said vehicle mounted DSRC apparatus further comprising data value matching means for matching the data value output from said second low pass filter with the ASK data value output from said first low pass filter when said QPSK modulator functions as an ASK modulator, wherein said QPSK modulator performs ASK modulation based on the respective data values which are input as the same value from said first and second low pass filters when said QPSK modulator functions as an ASK modulator in response to transmission data from one of said ground devices. 
 
     
     
       8. The vehicle mounted DSRC apparatus according to  claim 7 , wherein said second band limiting filter limits the band of said ASK data and the band of the other of said I data and said Q data in said QPSK data, and
 said data value matching means comprises: 
 said second band limiting filter; and 
 a filter property switching part for switching the filter property of each of said first and second band limiting filters in response to transmission data from one of said ground devices.